Evidence from NASA's Wide-field Infrared Survey Explorer and Galaxy Evolution Explorer missions provide support for the 'inside-out' theory of galaxy evolution, which holds that star formation starts at the core of the galaxy and spreads outward.

This image from NASA's Spitzer and GALEX shows the Helix nebula, a dying star throwing a cosmic tantrum. In death, the star's dusty outer layers are unraveling into space, glowing from the intense UV radiation being pumped out by the hot stellar core.

NGC 7293, better known as the Helix nebula, displays its ultraviolet glow courtesy of NASA's GALEX. The Helix is the nearest example of a planetary nebula, which is the eventual fate of a star, like our own Sun, as it approaches the end of its life.

Hot stars burn brightly in this new image from NASA's Galaxy Evolution Explorer, showing the ultraviolet side of a familiar face. Approximately 2.5 million light-years away, the Andromeda galaxy, or M31, is our Milky Way's largest galactic neighbor.

These images, taken with NASA's Galaxy Evolution Explorer and the Pan-STARRS1 telescope in Hawaii, show a brightening inside a galaxy caused by a flare from its nucleus. The arrow in each image points to the galaxy.

Time is running out for the galaxy NGC 3801, seen in this composite image from NASA's Galaxy Evolution Explorer and other instruments combining light from across the spectrum, ranging from ultraviolet to radio.

Dark Energy and Gravity: Yin and Yang of the Universe (Artist's Concept)

New results from NASA's Galaxy Evolution Explorer and the Anglo-Australian Telescope atop Siding Spring Mountain in Australia confirm that dark energy is a smooth, uniform force that now dominates over the effects of gravity.

This artist's concept illustrates a young, red dwarf star surrounded by three planets. NASA's Galaxy Evolution Explorer is helping to identify young, red dwarf stars that are close to us by detecting their ultraviolet light.

Astronomers have found unexpected rings and arcs of ultraviolet light around a selection of galaxies, four of which are shown here as viewed by NASA's and the European Space Agency's Hubble Space Telescope.

These two photographs were made by combining data from NASA's Galaxy Evolution Explorer spacecraft and the Cerro Tololo Inter-American Observatory in Chile to learn that not all galaxies make stars of different sizes in the same quantities.

NASA's Galaxy Evolution Explorer spacecraft and Cerro Tololo Inter-American Observatory combined data making this diagram illustratrating the extent to which astronomers have been underestimating the proportion of small to big stars in certain galaxies.